Paleontologist: studies life that existed in pre-historic times

Number from the first layer deposited to the last (most recent)

Sec FOSSILS Read pages 648 and 649. In your notebooks, answer the following questions. 1. What is a FOSSIL? 2. What are some EXAMPLES of fossils? 3. What are 5 ways that fossils FORM?

Fossils and the ways that they Form Section 29.1

Fossil: Any evidence of early life preserved in rock There are 5 basic ways that fossils form:

1. Original remains Bones, teeth Entire animals found frozen in permafrost Insects trapped in tree sap (resin)

Original remains of an insect trapped in the sticky, solidified tree sap (amber)

2. Replaced Remains Soft parts of plants or animals decays leaving a void Groundwater with dissolved minerals (calcite, silica, pyrite) fills the void The result is an exact copy of the original plant or animal Ex. Petrified wood: the soft wood decays and is replaced with minerals

3. Molds A leaf, plant, insect or organism is buried in mud or sediment. Leaves a shallow imprint or mold of the original shape. The mud or sediment becomes the rock shale or limestone A hollow depression (mold) of a brachiopod

3. Natural Cast Cast of a trilobite from the Paleozoic Era Minerals seep into a mold and fill-in the shallow imprint A 3-D copy of the original fossil alizations/es2901/es2901page01.cfm?chapter_no=29 Video clip of a mold and cast

4. Trace Fossils Indirect evidence of life, such as a footprint, worm hole, trails, tracks or burrows

4. Carbonaceous Films Sometimes all that is left is a thin carbon film Heat and pressure cause a chemical change in the carbon compounds of the organism

Finish your lab and label each fossil as: 1.Original remains 2.Replaced remains 3.Molds / casts 4.Trace fossils 5.Carbonaceous films

Bellringer: Match the following: a.Leaf print in shale b. Sharks tooth c. Worm holes d. Dinosaur bone e. Petrified wood 1.Original remains 2.Replaced remains 3.Molds / casts 4.Trace fossils 5.Carbonaceous films

Do all living things form fossils? NO! Some Conditions favor preservation:  Rapid burial in soft sediments like mud that forms shale or sea-floor sediment that forms limestone  Possession of hard body parts such as shells, exoskeletons, bones, teeth

Figure The Geologic Time Scale om/watch?v=j2r55qC PbDo

E___ P______E_________myaGeological events Phanerozoic _______% of Earth’s history 540 mya ______zoic (recent) Age of the ______________ 65 _______zoic (middle) Age of the ______________ ________zoic (ancient) Age of ____________ Age of _____________ Age of _____________ Cambrian

Pre-Cambrian (page 673) ________% of Earth’s history Stromatolites: Shields /cratons: Volcanism; Atmosphere: (pg. 366) 540 mya 4.5 bya

Humans Mammals Dinosaurs Early reptiles Then fish and amphibians First just aquatic creature Principle of Faunal Succession: Living organisms succeed one another in a definite order on the Geologic Time Scale

Geologic time scale  Divides geologic history into units  (Like a really long calendar, only not equal divisions)  Originally created using relative dates  Subdivisions Eons Eras –Periods »Epochs

Cratons: Some of the original continents were bits and pieces of land masses page 673

Precambrian fossils?

Stromatolites A layered dome or column formed from mats of blue green algea or cynobacteria. Age 3.5 billion years old

Other creatures existed on Earth for hundreds of millions of years before they went extinct. Some organisms lived on Earth a short amount of time (a few millions years) before they went extinct. If we know when they lived, we can use those fossils to help us determine the age of the rock that they died in. Scientists use fossils to determine the ages of rocks Index fossils must be: Unique Plentiful Easily identifiable Occur over large area Lived during a short time span

In which layer of rock strata were Rocks 1, 2 and 3 found?

1.Use an O to show the origin of an organism living on earth, X to show the end. 2.Assemblage = group or organisms living together. Assemblages form a Unique Group when one dies off and another is just starting to live (only found in that time period). 1.Use colored pencils. Use the same color for assemblages found across different rocks (=correlation). Use different colors for different assemblages!

First….. A B C Layers A,B,C, were laid down in succession. Layer A was deposited first, then B, then C.

Then they were uplifted and folded

Then glaciers moved through eroded the top

Then new layers of sediment were deposited on top at different times